An example of conventional separation devices is disclosed in Patent Document 1. In the separation device disclosed in this document, first, a defective piece of disposable diaper or the like in which a water-absorbent member is filled in an exterior material is cut into pieces of a predetermined size by a cutter. Then, the cut pieces are fed into a separator by pneumatic conveyance.
The separator has a rotational shaft that is provided so as to be rotatable about its axis and a cylindrical mesh unit that surrounds the rotational shaft and that is provided so as to be rotatable concentrically with the rotational shaft in an opposite direction. The rotational shaft is provided with a plurality of stirring rods that are disposed radially. The cut pieces that are fed into this separator are divided into the exterior material and the water-absorbent member by the rotational axis and the cylindrical mesh unit rotating in mutually opposite directions. The water-absorbent member is sifted out by meshes of the cylindrical mesh unit.    Patent Document 1: JP H8-117688A